Inter alia from EP-A-636463 by the Applicant, sandwich panels which have been manufactured in situ are known, which comprise a thermoplastic foam core layer which is connected to at least one—optionally fiber-reinforced—thermoplastic cover layer, as well as a method for the manufacture thereof. The term in-situ manufacturing is understood to mean forming the foam core layer in one step and connecting it to at least one cover layer in a press, starting from an assembly comprising a layer of a thermoplastic which is impregnated with a suitable physical blowing agent and comprises the at least one thermoplastic cover layer. This assembly is placed in a press and, once the material-dependent foaming temperature has been reached, the distance between the press platens is increased. Following cooling and drying, an in-situ manufactured sandwich panel is obtained. Because of their favorable strength and weight properties, such sandwich panels are particularly suitable for use in the transport sector, such as in aviation and space travel.
Nowadays, there are also thermoplastic sandwich panels which comprise at least one fiber-reinforced thermoplastic cover layer and a core layer made of a thermoplastic honeycomb structure. This honeycomb structure comprises essentially parallel open tubular elements made from a thermoplastic which are at right angles to the main surface of the fiber-reinforced thermoplastic cover layer.
With some intended uses of (thermoplastic) sandwich panels, the expected load is quite considerable and thus there is a need for construction elements of this type which have improved strength properties.